Some users may find it convenient to incorporate additional content into printed documents. Readers of the printed documents can then access the additional content and augment the information presented in the document itself. For example, user may want to add various types of external content in an electronic form to the printed document.
Previous attempts to allow users to add additional content into printed documents have been hard to use. In particular, it has been hard to create augmented documents that include additional content in a printed document. Readers may also have trouble reading the printed document or accessing the additional content. The previous attempts may also restrict when and how the additional content is added to the printed documents.
In addition, it has been difficult to impose more fine-grained control over access to the additional content into the printed documents. In other words, previous methods may provide no security at all to the additional content or be restrictive on what kind of security is used or how much security is used to control access to the additional content.